The 31-year-old defender commonly known as Zanka was without a club after leaving Turkish side Fenerbahçe S.K. this summer.
Zanka's move to the Bees is subject to confirmation of a work permit and international clearance with a club option to extend the deal until the summer of 2023.
Thomas Frank, Brentford FC Head Coach, said: “We are pleased that we could strengthen our squad and bring in a top quality experienced player to the group. This was especially important after Mads Bech picked up an injury.
“Zanka brings a wealth of experience from different leagues and a lot of international games, he has also played in the Premier League before. That experience and leadership is especially important, and it is great to get him in. Zanka is player that is defensively strong, he is aware of how we like to defend, has very good positioning and has quality on the ball. We think he can play in any of the three central defensive positions.”
Brentford are yet to lose their first game of the season after beaten Arsenal in the season opener and drawing two games.
The Premier League newcomers will look to maintain their unbeaten run when they play Brighton at Brentford Community Stadium on Saturday.
Zanka has featured 35 times for Denmark and was part of the squad that reached the Semi-Finals of the Euro 2020.
He also played, and scored one of his two international goals, for Denmark in the 2018 FIFA World Cup in Russia.